51720061 has 4 divisors (see below), whose sum is σ = 51833692. Its totient is φ = 51606432.

The previous prime is 51720037. The next prime is 51720073. The reversal of 51720061 is 16002715.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16002715 = 5 ⋅3200543.

It can be written as a sum of positive squares in 2 ways, for example, as 31416025 + 20304036 = 5605^2 + 4506^2 .

It is a cyclic number.

It is not a de Polignac number, because 51720061 - 2⁵ = 51720029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51727061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56130 + ... + 57043.

It is an arithmetic number, because the mean of its divisors is an integer number (12958423).

Almost surely, 2^51720061 is an apocalyptic number.

It is an amenable number.

51720061 is a deficient number, since it is larger than the sum of its proper divisors (113631).

51720061 is a wasteful number, since it uses less digits than its factorization.

51720061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113630.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 51720061 is about 7191.6660795674. Note that the first 3 decimals coincide. The cubic root of 51720061 is about 372.5801181961.

Adding to 51720061 its reverse (16002715), we get a palindrome (67722776).

The spelling of 51720061 in words is "fifty-one million, seven hundred twenty thousand, sixty-one".